ANGA COM 2020

ANGA COM 2020Online Event

17-November-2020Trimble

Time & FrequencyDivision

Synchronization Concepts

Trimble confidential, ©2020 Page 2

transformingTHE WAY THE WORLD WORKS

A world leader in transforming how work is done, across multiple industries and professions

Our customers gain significant economic breakthroughs at the same time improving quality, regulatory, specification compliance and reducing costs

Our technological capabilities in GNSS are unsurpassed in the industry, with a 40-year history in GNSS systems, positioning and timing… THE GNSS Experts!

2019 Revenue $3.2+ Billion USD; 11,000+ employees worldwide Deep knowledge of communication systems synchronization and

mission critical requirements Technology supplier to:

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Headquartered in Sunnyvale, California with facilities in 40 countries, partners in 125 countries and customers in 150 countries


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Time & Frequency

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transformingTHE WAY THE WORLD WORKS – ACROSS MULTIPLE INDUSTRIES & PROFESSIONS


Business OrganizationThe businesses are now organized into five major groups:

Autonomy Business Unit includes the following divisions: Advanced Positioning Applanix InTech (Precision GNSS) Embedded Technologies Autonomous Solutions Time & Frequency

Autonomy

Organized in Q4 2019


3 Types of Timing Absolute Timing / Synchronization

– What time is it at your place, in your timezone? Timestamps Time of Day (ToD) Coordinated Universal Time (abbreviated to UTC) is the primary time

standard by which the world regulates clocks and time Frequency Timing / Synchronization

Phase Timing

o The number of cycles per unit time, clocks running at the same rate and the ability to distribute precision frequency around a network

o Used to “synchronize” transmitters and receivers in communications systems

o Alignment of rising and trailing pulseedges in time

o Will be key to 5G, LTE-Advanced and TDD


There are "Master" clocks and "Slave" clocks– Masters (servers) provide timing; slaves (client) receive timing

Ordinary Clock (OC)– End device on network; there are 3 flavors:

1. Slave-only clock (receiving timing from a master)2. Grandmaster: only acts as a master, never as a slave

o GM has a good oscillator and the ability to obtain standard time (UTC), often GNSS receiver3. Master clock or slave clock

o This type of OC can act as either a master or slave; usually acting as a slave, unless there is no better master available in the network, in which case it takes over that function to become the GM (Best Master Clock Algorithm)

Boundary Clock (BC)– A BC has one port which acts as a slave (getting time from an upstream master),

and all other ports act as masters to downstream clocks to disseminate time to downstream slaves

Transparent Clock (TC)– A TC provides hardware timestamps whenever a sync message arrives or

departs to adjust for packet delay 1-Step Clock versus 2-Step Clock

– 1-Step clock: the timestamp from the master clock is included in the first “sync" message sent master slave

– 2-Step clock: the timestamp from the master clock is sent in a separate message after the "sync" message has been sent

Clock Types


First it was Backhaul:– 2G, 3G– Connecting cell site, base station radios to the network

switching elementso 2G (GSM): BTS BSC "Core"o 3G (UMTS): NB RNC “Core”

Then came Fronthaul– 4G (LTE-A): RRH (eNB) BBU– Connecting cell site radios to a geographically

distanced baseband unit– BBU "Core" = backhaul

Now there is also Midhaul– 5G NR: RU (gNB) DU = fronthaul– DU CU = midhaul– CU "Core“ = backhaul

"Anyhaul" Defined


The DOCSIS 3.1 architecture introduced the need for an industry standard PTP Grandmaster clock (IEEE-1588v2) to providing timing to the CMTS and RPDs

– The GM can be used to synchronize both the CMTS and RPDs, whereby the timing is decoupled from the CMTS itself to simplify its design and offload timing performance to a high-quality timing source (GM) for better accuracy and reliability.

– DOCSIS Timing Protocol (DTP) introduced for more accurate timing and a mechanism to measure/model the asymmetries in the HFC network, as well as provide an adjustment factor to the DOCSIS timestamps

– 2021 will introduce the requirement to support phase sync over DOCSIS with partial network (G.8275.2 PTP profile)

DOCSIS Sync Architecture


IEEE-1588v2 Time Transfer TechniqueMaster Clock Slave Clock

The process is repeated up to 128 times per second.(Announce rate is lower than Sync rate)

Switch/R

outer Layer

Time

Time

t2

t3

Data AtSlave Clock

Leap second offset

t2 (& t1 for 1-step)

t1,t2

t1, t2, t3

t1, t2, t3, t4

Round Trip DelayRTD = (t2 - t1) + (t4 - t3)

Offset:(slave clock error and one-way path delay)

OffsetSYNC = t2 – t1 OffsetDELAY_REQ = t4 – t3

We assume path symmetry, thereforeOne-Way Path Delay = RTD ÷ 2

Slave Clock Error = (t2 - t1) - (RTD ÷ 2)

Notes:1. One-way delay cannot be calculated

exactly, but there is a bounded error.2. The protocol transfers TAI (Atomic Time).

UTC time is TAI + leap second offset from the announce message.

t1

t4


G.8265.1 PTP Telecom Profile enables the deployment of PTP-based frequencysynchronization by telecoms operator

G.8275.1 is aimed at new build networks– Furnishes both frequency and phase synchronization– Requires boundary clocks at every node in the network

G.8275.2 is aimed at operation over existing networks– Furnishes both frequency and phase synchronization– Permits Boundary Clocks (BCs) or Transparent Clocks

(TCs), but are not required– BCs placed at strategic locations to reduce noise (e.g.,

PDV)

PTP Profile Comparison


PTP (IEEE-1588v2) Network Example


Mobile Network Timing Requirements The PTP Time Alignment Error (TAE) that was introduced for LTE-A macro and

small cells was +/- 1.5 microseconds of phase accuracy (per the 3GPP standard) Time Error Budget:

5G will have more stringent phase sync requirements (e.g., massive 5G NR, Massive MIMO, O-RAN); for example:o DU AU/RU = ±130 nso PTRC-B = ±40 ns


The Mobile Backhaul (MBH) Opportunity

The Opportunity: provide MBH for 5G small cells over the DOCSIS network

But why transport Mobile telephone traffic over DOCSIS? The CATV Operator HFC infrastructure provides the

following (competitive) advantages:o Ubiquity – HFC networks run down every street and to

every building in the cities, giving wireless planners significant flexibility to design optimal small cell deployments

o Power – HFC’s ability to provide (transport) power to small cells; i.e., power can’t be transported over fiber or microwave backhaul radios

o Deployment Speed & Simplicity – HFC architectures can facilitate fast small cell deployments


LTE RAN / Backhaul Evolution

C-RAN introduced the concept of Fronthaul

(CPRI), a TDM fiber connection between

Baseband units and Remote Radio Heads

eCPRI introduced Ethernet fiber into Fronthaul, along with functional Baseband split:

Distributed Unit (DU) & Central Unit (CU); RRH = Antenna Unit (AU)


A separation of the upper and lower parts of the RAN was standardized in 3GPP R15, where a higher-layer split was specified with a well-defined interface (F1) between two logical units: the Centralized Unit (CU) and the Distributed Unit (DU). The CU—with less stringent processing requirements—has been more amenable to virtualization than the DU and its functions that are closer to the radio.

For full-stack RAN virtualization, the DU is connected to the radio via a packet interface known as enhanced Common Public Radio Interface (eCPRI). There are multiple ways to divide functions between the DU and the radio; in standards discussions these are referred to as lower-layer split (LLS) options. One possible alternative specified by the O-RAN Alliance is referred to as the 7-2x split, but other functional splits are also being considered.

From: 5GPPP Architecture Working Group5G Architecture White Paper

Synchronization is required at the DU for distribution to the Radio Units (RUs)


The Basic MBH Evolution


Backhaul will change with 5G & O-RAN1. Fronthaul (DU to RU)2. Midhaul (CU to DU)3. Backhaul (Aggregation/Core to CU)

The New Mobile Backhaul


O-RAN SynchronizationPer ORAN-WG4.CUS.0-v02.00, § 9.2 Synchronization Baseline:

• Time and frequency synchronization can be distributed to the O-DU and O-RU in different manners

• Synchronization accuracy is mostly impacted by implementation (e.g., timestamping near the interfaces, number of hops)


O-RAN SynchronizationTrimble GM200


O-RAN Synchronization

TrimbleAcutime 360


Features:– IEEE 1588v2 PTP Grandmaster Clock and NTP v4 Time Server

Supports 64 Simultaneous PTP clients in PTP-only mode at 32 transactions per second (tps) Supports 2,500 NTP tps in NTP mode A PTP-only model also exists

– 15 ns time accuracy (one sigma) of GNSS / UTC– GNSS (GPS, Galileo, GLONASS & BeiDou)– Extended temperature operation (hardened)

-40° to +85° C (no fan or heater element)– Superior holdover performance

±1.5µsec 4+ hours (live tests have consistently seen as much as 20 hours after GNSS lock for 7 days)

– Multiple profiles supported IEEE-1588v2, G.8265.1, G.8275.1, G.8275.2, Telecom-2008, Power (IEEE C37.238-2011), Enterprise, Broadcast

(ST 2059-2:2015 SMPTE), IEEE 802.1AS− Assisted Partial Timing Support (APTS)− Boundary Clock (BC) operation supported– Two Gigabit Ethernet Interfaces: 1x RJ45, 1x SFP– One dedicated Management Port: 1x RJ45 (10 / 100 Mbps)– IPv4 and IPv6 Support– SNMPv3 Management– Web User Interface and CLI– Security: RADIUS, TACACS– Dual Power Input (-48VDC) provides power redundancy– Power Dissipation: 5 Watts typical; 10 Watts Max– Multiple installation options, including redundancy in 1 RU

½ RU unit; install two unit in a 19-inch, 1 RU space– Lowest price on market for feature set offered

ThunderBolt™ PTP Grandmaster GM200

Roadmap GM310 board with PTPMigrating GM200 features


GM200 Edge Grandmaster (a closer look)

GM200 Front Panel

RS‐232 Serial

PPS or 10MHz

Management Port (10/100 Base‐T)

RJ45 port (PTP and SyncE)

SFP port (PTP and SyncE)


GM200 Edge Grandmaster (a closer look)

GM200 Back Panel

GNSS input (SMA, Female) Power Input x 2 (‐48VDC)FrameGND

Alarm Relay


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contained in a IP67-compliant radome, roof-top enclosure

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Thank You

Robert PaganoSales & Business Development

[email protected]

Mobile: +39 346 654 0987www.trimble.com

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